jtm54

So i know very little about cyclorcross bikes and need some direction. I just purchased a frame that hast all the cable running along the top tube and and trying to figure out the best way to run the derailleur. Can a use a mountain style top pull FD (the one in mind is a Sram X0 low clamp) or do I need to find a pulley to use a road type FD? It appears like the frame has the spot for the pulley just doesn't have one on it. If where do I find one, my google skills have let me down?

Andy_K 

MTB front derailleurs typically use different cable pull ratios than road shifters, though with a double you could probably make it work. Shimano makes a CX specific top pull front derailleur, but I'm not sure about compatibility with non-Shimano shifters. Again, you could probably make it work. Otherwise, Problem Solvers makes a clamp on pulley for this.

RaleighSport

Last deore FD I bought was a top OR bottom pull FWIW.

GrayJay

An MTB FD will work if your large front chainring is not excessivly big. If you do want to run a 53t chainring, a road or CX specific FD is probably better. I would avoid using a pully & bottom pull FD, more stuff to clog-up and keep clean.

flargle

Shimano CX70. It comes in a variety of configurations, including top pull; make sure you order the correct one. I use it with Sram shifters, I have no complaints.

GrayJay

My one complaint about the new shimano CX series FDs is that they need a shim to be used with a 28.6mm seattube, smallest actual size offered is 31.8mm. I have a steel CX bike with 26.8mm seattube and was able to find older top pull MTB FD that fit the tubing without a shim and works fine with the rest of my drivetrain (46t chainring).

flargle

That is a bummer for the ferrously oriented.

flargle

(That said, they do make front der shims for those sizes and I bet it'd work fine.)

fietsbob

there are rollers that sit in place below the FD, to redirect the cable pull from front to bottom pull.

For CX some include a cover to keep the mud less on it..

you can fit a riv nut in the seat tube, to mount it , or there are band clamp ones, sold.

jtm54

Thanks for the help. Looks like I'm going to start with a pulley and cover set-up. I like the idea of a cx specific FD, might look into that down the road.